1. Field of the Invention
The present invention relates to a spool valve in which a spool is disposed in a valve chamber of a valve body having an inlet port and an outlet port formed therein.
2. Description of the Related Art
Heretofore, for example, in an air-jet loom in which wefts are made to fly out by jets of compressed air, a two-way valve has widely been used. With this type of air-jet loom, it is desirable for a high speed valve with a large flow rate to be used. However, in the case that a two-way valve is used, because a large force is required instantaneously, a disadvantage results in that the solenoid coil that makes up the two-way valve is large in size with a commensurate increase in power consumption. Further, with such a two-way valve, the discharge flow rate and pressure cannot be controlled.
A spool valve is known in which the discharge flow rate and pressure can be controlled. In such a spool valve, a spool is arranged in a valve chamber of a valve body having a plurality of ports formed therein, and a structure is provided in which the respective ports are opened and closed by displacement of the spool in an axial direction. In relation to this type of spool valve, a technical concept is known in which, by controlling a current supplied to a proportional solenoid disposed in the valve body, the spool is displaced directly and the pressure on the secondary side of the spool is steadily controlled (see, e.g., Japanese Laid-Open Patent Publication No. 08-285123).